It also make me think if it be would be possible for this model to work. Person 'A' and Person 'B' are two steemians. 'A' has little time on his hands and decides find a steemian who can use some delegated SP in a better manner. So 'A' finds that is 'B' a deserving candidate and delegates him some SP with a contract that both of them will share the curation rewards.

That's legit, and it's within my rules. A considers B to be a good curator, hence the first rule is obeyed - and even though A will get some returns from B, he's not just uncritically delegating to the highest bidder, hence the second rule is also observed :-)